Crop rotation

 

The principle underlying crop rotation is that there should be a considerable gap in time between plantings of veggies from the same family in the same place. This helps stop particular diseases building up and also gives the soil a rest from particular burdens placed on it.

Veggies can be divided into the following 8 ‘groups’ (most of which are families or sub-families):

  1. Legumes (beans, peas, etc).
  2. Alliums (garlic, onions, etc).
  3. Roots (beetroot, carrots, celery, parsnip, etc).
  4. Cucurbits (cucumber, pumpkin, rockmelon, zucchini, etc).
  5. Solanums (capsicum, chilli, eggplant, potatoes, tomatoes, etc).
  6. Brassicas (broccoli, brussels sprouts, cabbage, cauliflower, kale, mizuna, pak choy, rocket, etc).
  7. ‘Anywhere’ (basil, coriander, lettuce, radish, silverbeet, spinach, etc).
  8. Perennials (asparagus, globe artichokes, rhubarb, etc).

Perennials are not relevant to crop rotation – they should be planted elsewhere. The ‘anywhere’ group are also not relevant – just plant them wherever and whenever you have gaps. So, the ideal is a 6-bed, 6-year rotation for the other 6 groups.

The diagram shows a possible 6-year rotation. Let’s assume that alliums (onions etc) are planted in bed 1 in year 1. Then that bed would be planted with solanums in year 2, legumes in year 3, brassicas in year 4, roots in year 5, cucurbits in year 6, alliums again in year 7, and so on. And alliums would be planted in bed 2 in year 2, bed 3 in year 3, bed 4 in year 4, bed 5 in year 5, bed 6 in year 6, back in bed 1 in year 7, and so on.

If you have fewer beds, then you have to do one or more of three things:

  1. Combine some things: so, for example, plant alliums and roots in the same bed.
  2. Omit some things: so, for example, never plant brassicas.
  3. Plant a cool season crop (e.g. brassicas) followed by a warm season crop (e.g. beans) – or vice versa – into a single bed over the course of a year.

You then have to decide the order of how a bed should change over time. A principle here is that heavy feeders should, where possible, alternate with light feeders. So, for example, alliums (light) – solanums (heavy) – legumes (light) – brassicas (medium) – roots (light) – cucurbits (heavy).

Finally, you have to choose whether the annual rotation should be in Spring or in Autumn.

For a longer discussion of crop rotation, read Robin Gale-Baker’s article on the subject.

  23 Responses to “Crop rotation”

  1. Hi! I am very new to all this. I have just planted my first ‘winter garden’ here is the U.S. Southeast, between Thanksgiving and Dec 7. Of all of the crop rotation systems I reviewed, I really love the clarity and number of years / seasons of this 6-bed chart, and plan to follow it. Since I mostly planted brassicas / cole crops and lettuces, it looks like I would follow them with root vegetables. My dilemma is that those also seem to be cool season crops. I don’t expect to have harvested very much in time to plant those items, and roots are not usually really great transplants, I think, right? Would I wait until the next cool season, and skip a summer garden in 2024? Or perhaps – what would happen if I skipped roots and went to cucurbits (I have a feeling that’s not so good.)

    I recognise celery may be one option, but I couldn’t do all of my beds with just that! Any ideas or suggestions are greatly appreciated – thank you!

    • Hi Heather,

      Aiming for two crops in a bed within a year is a challenge for any crop rotation system, if only because when one wants to plant the next crop, the previous crop is sometimes not ready for harvesting. But I don’t agree that root vegetables are cool season only. Here in Melb ourne Australia, we can plant beetroot all year round, carrots are more warm season than cool season, some leeks are warm season, most onions are more warm season than cool season, parsnip are warm season, potatoes are more warm season than cool season, and sweet potato is warm season. See our planting guide (https://localfoodconnect.org.au/community-gardening/planting-guide/).

  2. I attempt crop rotation, but not necessarily in the correct order or the years between, due to not understanding the family groupings very well – eg: I wouldn’t grow tomatoes in the same bed the following summer and would grow a winter crop of some sort in between but I don’t always get it right from the right family grouping
    I have been doing this for a few years and am in a bit of a muddle now and would like to correct it.
    What is the best way or what should I plant as a break crop for a season to replenish the beds and start a proper rotation system from now on?
    Also I believe I have ‘white rot’ affecting my garlic and Onions (turning them to mush) – I used to be able to grow good ones.
    I gather it stays in the soil for a long time – any suggestions to get rid of it or is their something else I can plant instead in the Alium grouping?
    I would appreciate your advice.

    • Hi Lyn,

      I think that you should just start rotating rather than take a season’s break.

      Re alliums, what are your rotation groups? I combine all root crops into the same group so, instead of alliums, you could plant carrots, parsnips or beetroots.

  3. Hi Guy,
    I hope you are well.
    I was just wondering how crop rotation works when you have done companion planting.
    For example: I had beans growing with cucumbers and I also had carrots in between. So in that area I had roots, cucurbits and legumes together.
    Could you advise what you would plant in that area next please?
    Thanks,
    Gav

    • That is a good question, Gav!

      As your example illustrates, crop rotation and companion planting don’t really go together and you basically have to choose one or the other. For me, I don’t find it a diffkicult choice.

  4. My green beans are done. How long do I wait before planting from the Brassicas group? I live in Perth.

    • From a soil point of view, you don’t have to wait at all. But most brassicas are a cool season crop which are grown over winter.

  5. Where does corn go?

    • Hi James,

      That is a good question. You just have to choose a group within which to put sweetcorn. I put it with my cucurbits.

  6. Hi Guy, thanks for all the helpful information. Given that some crops are winter crops and others are summer crops, what do you recommend is the best thing to do in between these crops, in those beds? Would that be a good time to plant lettuce, spinach and herbs? Thanks, Natalie

    • Hi Natalie,

      What an excellent question!

      If you are only trying to grow one ‘crop-rotation crop’ in a particular bed in a particular year then, yes, plant your leafy greens in the time gaps. If you still have spaces then you can also plant legumes and (I think) alliums, as these don’t deplete the soil much.

      If, like me, you want to grow two ‘crop-rotation crops’ in some beds in some years, with the movement of the crop rotation happening between these two crops, then the issue of gaps doesn’t really arise. Rather, the issue here is that one often wants to plant the second crop before the first crop has been fully harvested, and one needs to juggle things to manage this. This is, for example, why I haven’t planted out my tomatoes yet.

      Guy

      • Thanks Guy, this leads me to another question (or two)!

        You mentioned growing two crops in some years; I’ve been wondering about whether it’s okay to plant successive crops of the same family in the same year before the rotation – e.g. for brassicas planting kale in summer and broccoli etc in winter, or for legumes planting green beans in summer and broad beans in winter.

        Alternatively, does each rotation have to be a full year or could you, for instance, plant tomatoes in summer followed by legumes in winter and brassicas the following summer in the same bed?

        Hope this makes sense! It’s complicated once you get into it. NB I dedicated a bed to alliums and root vegetables, planted beetroot, radish and horseradish then realised they aren’t from the root family at all, nor are turnip or potato (they come from the spinach/silverbeet, brassicas and solanum families, respectively). That’s stuffed that bed up a bit!

        Thanks again for all your help,
        Natalie

        • Hi Natalie,

          I think that most people only move their rotations once a year. I move mine between the Winter and Summer crops and thus grow green beans followed by broad beans or peas in my legume bed.

          I think that basically anything where you eat the root should count as a root in terms of crop rotation because they all break up the soil in a similar way. Potatoes are the exception: for various reasons, I think that you grow them elsewhere rather than in your veggie patch.

  7. Indicative of what? If you don’t want to do crop rotation, don’t do it. If you google something like “crop rotation scientific control study”, all sorts of studies appear which you can read the results of. I’m not aware of any small scale farmer or serious home grower who continues to grow the same crop in the same place year after year.

  8. I have seen the detailed recommendations and rationales for crop rotation in many sources. My question is, ‘does anyone know of any scientific, controlled studies of crop rotation as it applies to vegetable gardens (as opposed to big agricultural operations doing acres of a crop and using green manures in off seasons)?’

    I would love to believe this theory but the only controlled study I know of was that of Charles Dowding, English market gardener and author. And his results contradicted the need for rotation. Anyone?

    P.S. Please don’t repeat the rationales, I know why it is supposed to be useful. It’s just that often we find that our beliefs are not correct.

    • Dave,
      I came here after asking the google the same question. I suspect the dearth of replies is indicative.
      Such zeal from so many information sources for this wive’s tale.

      • Indicative of what? If you don’t want to do crop rotation, don’t do it. If you google something like “crop rotation scientific control study”, all sorts of studies appear which you can read the results of. I’m not aware of any small scale farmer or serious home grower who continues to grow the same crop in the same place year after year.

    • Would alternating growing green manure with mono crops be considered as crop rotation?

    • Keep in mind Charles Dowding has massive amounts of compost, which he dresses his beds with. Most home gardeners don’t have access to this amount of compost — green manure crops replenish the beds in lieu of inches of added compost.

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